Apparatus for continuously measuring the combustible constituents of waste gases



M. MOELLER APPARATUS FOR CO'NTINUOUSLY MEASURING THE' COMBUSTIBLECONSTITUENTS OF WASTE GASES Filed Nov. 22, 1924 1mm wwwuw Patented Nov.17,1925.

UNITED STA y GESEIJLSCHAFT, OF SIEMENSSTAD'I, NEABBERLIN; GERMANY a nnt-Montana, or BERLIN, GERMANY, Assle'Noa-ro vsimmmsa nansxn -axrxnnnrranarus roa coN'rINUoU'sLii MEASURING rim cemu nm boas-meme or '7'was'rneasns. 1

Application filed November 22,1924. Serial No. 751,7

To all whom'z'zt may mm:

zen of" the German Empire, residing at Berlin; Germany, have inventedcertain new 6 and usefulImprovement's iu-Apparatusfor -ContinuouslyMeasuringthe Combustible Constituents of Waste Gases,. ofwhich thefollowing is.a specification; I f

My invention relates to improvements in apparatus for continuouslymeasuring the combustible constituents of waste gases of furnaces orinternal combustion englnes In order to be able to supervise furnaces orinternal combustion engines. in regardto the completeness of thecombustion oftheir fuel, apparatus has been provided which enable thewaste gases to be tested in regard a to their contents of combustible.constituents. I r My invention consists in providing for the continuousmeasurement of these combustible constituents an electrically heatedcata-- lytically acting wire which consists of an alloy containing atleastone of the elements of the-platinumgroup (including broadlyplatinum, iridium, osmium, palladium, ruthenium and rhodium) and whichis so connected with a resistance -measuring arrangement that itsresistance can ,be read.

off on a measuring instrument or be recorded by saidinstrument. Thetemperature rises taking place in the wire when the combustibleconstituents of the vwastegases are burned cause an increase of itselectric resistance which is measured by one of the known arran ementssuch as a Wheatstone bridge and t e values obtained are utilized as ameasure for the combustible constituents still contained in the wastegas] v In the drawing afiixed to this specification and forming-partthereof an embodiment of m illustrated by way of exam le.

Referring to this drawing, 2 is a tube through whichthe waste gases tobeexamined are conducted while a tube 1 contains atmospheric air forcomparison. Betweenthe terminals 3 and 4 a platinum-iridium wire 9 andbetween the terminals 5 and 6 o a platinum-iridium wire 10 is stretchedand kept in astate of tensionby the springs 7 and 8 respectively. Thetwo wires 9 and 10 are with one end connected with the branching points13 and 14 by the wires 11 and 12 Be it known that I, LLixMOELLfiR, aciti measuring wires may be employe is of importancein view of thehighgost invention isdiagrammatically and with theirother end withthepoint 16" of {a Wheatstone bridge arrangement; "Besides the standardresistancesbetweenthe points- 13 and 15 and 148ml 15 thesys'temcontainsa1 Source of; current 18 alid a fresistance; "measuring' 1nstrument -17which may also be haveno disturbing efl'ect on the apparatus it'isnecessary that the catalytically acting Wire should always maintain thesame distance 'fiomthe Walls of the tubes. On account of the stretchingof the-wire with the increase in'temperature the wire must be subjectedto such a preliminary tension that sagging is avoided with certaintywhether the wire be stretched across in a straight line or whether'it bein helical form. To fulfill these conditions a wire consisting of pureplatinum would have to have a considerable cross-sectional area, Theconsequently comparatively low electric resistance of such a wire woundin itself require'strong electric currents "for its heating and theaccuracy of the resistance measuring arrangement would be reduced. Allthese'dr'awbacks are efl'ecing of an alloy containing at least one ofthe elements of the platinum group (for instance .tively obviated if ameasuring wire consistplatinum-irridium .orplatinum-rhodium) 'isemployed because such a wire has a "con'-.

siderably greater tensile strength and an about 4 to 8 timeshigher'specific electric resistance.

Owing to which of the material in question. Aconsiderable reduction inthe consumption of current is, furthermore. attained since theresistance increases not only inconsequje'nce of the smallercross-section but also in consequence of the electric properties of thematerial. Inview of the fact. that these apparatus. are permanentlyconnected incircuit a low current consum tion is frequently decisive fortheir introduction into 1 practical use. The resistance of the saidalloys against chemical influences is "also considerabl the greatertensile stren h thin greater than that of pure platinum whie in I is avaluable feature in view of the chemie :7 cally highly corrosiveconstituents of waste 'ggases.

with a suitablefgas'for comparison with the Waste gases and containing awire of suitable catalytically acting material surrounded by saidcomparison gas,'a second 7 compartment having, an intake and .adischarge opening Vfor said wastegases, and

containing a catalyti'cally acting'wire con si'sting of an' alloycontaining at least one of the'elements of the platinum group, said wirebeing surroundedby said waste gases,

' v a source'of current and conductors for con- 7 nectingsaid'source wth sa1d catalytic w res,

v paring the amount of current passing -and a measuring instrumentsuitably connected in circuit with said'wires for comthrough said wires.

2.- In a device for continuously measur- V ingnthe combustibleconstituents of Waste 'ga'ses' the combination of a compartment filledwith a suitable gas for comparison withthe Waste gases and containingawireof suitable catalytically acting material sur: rounded bysaidcomparison gas, a second compartment having'an intake and a dischargeopening for said waste gases, and

sisting of an alloy containing at least one of the elements of theplatinum group, said wire being surrounded by saidlwjaste gases,

'a source of current and conductors for con- "nectlng said source withsaid GEltEllytlQWlIQS containing a' catalytically acting Wire 0011- andameasuringinstrument connected in a Wheatstone bridge connection, withsaid wires for comparing theamount. of current passing through'saidwires vIn testimony whereof I afiix my signature.

VMAXMOELLER.

